I am a big fan of FactCheck.org. I think they do solid work analyzing the veracity of political claims and ads. I also think that their analysis of the debates has been valuable and even-handed. In their analysis of last night's vice-presidential debate, however, I think FactCheck.org got one wrong.
On the issue of the proportion of casualties in Iraq borne by the U.S., FactCheck.org reported the following:

Cheney disputed Edwards's statement — often repeated by Kerry — that US forces have suffered "90% of the coalition casualties" in Iraq, saying that in fact Iraqi security forces "have taken almost 50 percent" of the casualties.
Both men have a point here, but Edwards is closer to the mark.
Edwards is correct counting only "coalition" forces — those of the US, Britain and the other countries that took part in the invasion and occupation of Iraq. According to CNN.com, which keeps an updated list, 1,066 US service men and women had died from hostile action and other causes during the Iraq operation as of Oct. 5, of a total 1,205 for all coalition countries. That's just over 88% of the coalition deaths.
We know of no accurate count of deaths suffered by Iraqi security forces, but an estimate reported both by the Wall Street Journal and The Washington Post puts the figure at 750. Lumping those estimated Iraqi deaths with fatalities suffered by coalition forces produces a total of 1,955. Of that, the estimated Iraqi portion is 38% (not "almost 50%" as Cheney claimed) and the US total amounts to 55%.

FactCheck.org got the numbers right as far as I am aware. The problem, however, is that FactCheck.org materially misrepresented what Vice President Cheney said. Here is what he said, taken from the debate transcript:

Well, Gwen, the 90 percent figure is just dead wrong. When you include the Iraqi security forces that have suffered casualties, as well as the allies, they've taken almost 50 percent of the casualties in operations in Iraq, which leaves the U.S. with 50 percent, not 90 percent.(cmphasis added)

It is clear from the above that Cheney did not claim that Iraqis accounted for "almost 50%," but rather that Iraqis and other coalition members combined, accounted for "almost 50%" of casualties in Iraq, leaving the U.S. with the other 50 percent. FactCheck.Org's selective highlighting of the relevant passage from Cheney's remarks furthers the misrepresentation.
Again, I generally think the folks at FactCheck.Org do a stand up job. But this time they got one wrong.
Update: In response to reader e-mail, let me offer this clarification. In the post above I am not claiming that Senator Edwards' numbers were wrong. So it is fair to say that Cheney overstate his substantive point when he called Edwards' claim "dead wrong." Cheney's point — as the full exchange makes clear — was not that Edwards was using a false number, but rather that Edwards was using an inappropriate measure of the relative U.S. contribution because he was excluding relevant casualties. My point is not that Cheney's measure was more or less appropriate than that offered by Edwards. Rather, it is that FactCheck.Org's claim that Cheney's number was false is based on a clear misreading of Cheney's words. It is one thing to say that Edwards number was correct, and Cheney's number is inappropriate — as some readers have — it is another to (falsely) claim that Cheney's number is inaccurate. As FactCheck.Org's own calculations make abundantly clear, if coalition and Iraqi security force casualties are combined they account for almost 50 percent of the total casualties — and this is what Cheney said.
One other point worth noting: In the exchange, both Cheney and Edwards referred to casualties. When it came to Iraqi casualty numbers, however, FactCheck.Org used "deaths." As one reader notes, however, casualty counts typically include all those lost to active service, not just those who are killed, so FactCheck.Org may also have undercounted the total number of Iraqi casualties by only reporting deaths. If readers have additional insight on this point, I will post another update.
Update: The VC gets results. FactCheck.Org amends its post.